10 



capturing the animal, the shell was unfortunately hroken, one of the fragments 

 still continued to adhere to the muscle, and this part is so represented at h. pi. 1 . 



The impression of this girdle, and particularly of the lateral expanded portions, 

 or the muscular impressions, may be observed in the interior of the shell near 

 the bottom of the external cavity. Occasionally a layer of the dark-coloured 

 horny matter adheres to the naker, especially in recent shells, of which I have 

 had an opportunity of observing a fine example (through the well-known libe- 

 rality of the possessor,) in the choice cabinet of W. J. Broderip, Esq. F.R.S. &c. 

 V.P.G.S. 



From the extremity of the sac is continued a small tubular membranous pro- 

 cess (^. pi. I ; d. pi. 5.), which passes through the siphonic apertures in the 

 septa of the shell, and is continued, there is reason to beUeve, to the innermost 

 chamber. This tube has been surmised to be tendinous or muscular ; but the 

 attachment of the shell to the soft parts proves to be eflected by much more 

 adequate means. Rumphius* appears to have been acquainted with its true 

 structure, for he calls it an artery {een langen ader), and in fact within the ex- 

 ternal thin membrane are included a small artery and vein. How far these ves- 

 sels are continued within the chambered portion of the shell, or in what manner 

 they are distributed, remains for some future investigation ; for in the present 

 instance the only part of the shell that was preserved was the small portion ad- 

 hering to the horny tendons, and the membranous tube had been ruptured, in 

 removing the animal, at a few lines distance from its origin at the mantle. This 

 tube appears to be contracted at its origin, and its diameter at the wider part is 

 one line and a half. 



Tlie infundibulum, funnel, or vent-tube {k. pi. 1 ; /. pi. 2. & 5.), projects for- 

 ward through the aperture in the under and anterior part of the mantle, to the 

 extent of two inches. It has the form of a depressed or flattened cone with the 

 apex directed forwards, and at each side of the base there is an obtuse and 

 wrinkled process {I. pi. 1 ; d. d. fig. 2. pi. 3 ; g. g. pi. 5.) : its breadth at the 

 base is one inch and a half. 



Tlie funnel is not, as in the Dibranchiate Cephalopods, a tube with entire 

 parietes, and open only at the extremity, but is formed by the overlapping of the 

 margins of a thin fleshy substance, so that when these margins are divaricated, 



* D' Amboinische Ruriteit-kamer, p. 60. 



